1. Field of the Invention
The present invention is directed to pre-formed building panels that include one or more reinforcing structural elements embedded in a foamed thermoplastic matrix.
2. Description of Related Art
It is known to use construction elements made of expanded plastics, for example expanded polystyrene, in forms of boards or section members of suitable shape and size. These members provide thermal and sound insulation functions and have long been accepted by the building industry.
It is also known that, in order to confer adequate self-supporting properties to such construction elements, one or more reinforcing section bars of a suitable shape must be incorporated into the mass of expanded plastics.
U.S. Pat. Nos. 5,787,665 and 5,822,940 disclose molded composite wall panels for building construction that include a regular tetragonal body of polymer foam and at least one light metal gauge hollow stud in the body. The edges of the studs are even with a surface of the polymer foam so drywall can be attached thereto.
U.S. Pat. No. 6,098,367 discloses a constructive system applied to buildings to form walls by means of modular foldable frames that allow for the placement of blocks or plates. The frames with the resistant channels, rods, blocks or plates, better resist strong winds and seismic movements.
U.S. Pat. No. 6,167,624 discloses a method for producing a polymeric foamed material panel including the steps of providing a polymeric foamed material, cutting the polymeric foamed material until reaching a preconfiguration cut point, cutting subsequently from the preconfiguration cut point a brace-receiving configuration in the polymeric foamed material, and sliding a brace member into the brace-receiving configuration to produce a polymeric foamed material panel.
U.S. Pat. No. 6,235,367 discloses a molded construction product, having one or more walls and an inner core section, including a composition matrix having a resin system, a catalytic agent, and filler compounds for forming the walls; a foam core system for forming the inner core section, a curing agent and a drying agent. A structural reinforcement support system is provided for reinforcing the structural integrity of the composition. A locking system is provided for joining one or more of the molded products.
EP 0 459 924 discloses a self-supporting construction element made of expanded plastics material, specifically a floor element, which includes a substantially parallelepipedic central body in which a reinforcing section bar, made of a thin metal sheet shaped as an I-beam, is integrated during the molding step.
U.S. Pat. No. 5,333,429 discloses a composite panel with a structural load-bearing wooden framework formed by a substantially parallelepiped body of expanded synthetic material. The panels have a plurality of longitudinal channels extending for the whole height of the panel. A series of channels uniformly spaced and staggered are open on the adjacent face of the panel and have a T-shaped cross section. In these open channels fit T-shaped cross section wooden posts, the stem portion of which emerges out of the open channels and project from the surface of the panel.
WO 2002/035020 discloses a composite construction element that includes a body made of expanded plastics material and a slab-shaped coating element associated to the body. The slab-shaped coating element includes a plurality of substantially adjoining and substantially U-shaped adjacent sections provided with respective means for mechanically clinching the slab-shaped element to the expanded plastics material.
While the construction elements described above have on the one hand light weight, comparative ease of installation and low cost, on the other hand their application in the art and flexibility of use have been restrained heretofore by their poor fire-resisting properties and/or the propensity for mold to grow on finished surfaces attached thereto.
This inadequate resistance to fire is essentially related to the fact that construction elements made of expanded plastics show an insufficient capability to securely hold outer covering layers, such as the plaster layers used for the outer surface finish or contain the expanded polymer body, in flammable molten or liquid form, that occurs from the heat generated from a fire.
When exposed to fire, in fact, the expanded plastic materials soon shrink into a shapeless mass of reduced volume, which can flow and burn, and in some cases with the ensuing separation of the outer covering layers and rapid collapse of the whole structure.
In addition, an undesirable separation of the outer covering layers may be caused in some instances by a premature “aging” of the plastics surface to which these coverings adhere, a separation which may be further fostered by exposure to heat sources, dusts, fumes, vapors, or chemical substances coming from a source close to the construction elements.
U.S. Pat. No. 6,298,622 and WO 2004/101905 disclose an approach to overcoming the above-described problem by using a self-supporting construction element of expanded plastics for use as floor elements and walls of buildings. The construction elements include a central body, substantially parallelepipedic in shape and having two opposite faces; at least one reinforcing section bar transversally extending across the central body between the faces thereof and embedded in the expanded plastics; a lath for supporting at least one layer of a suitable covering material, associated to a fin of the reinforcing section bar lying flush with and substantially parallel to at least one of the faces of the construction element. However, moisture buildup between the lath and construction element can lead to mold and mildew growth and the ability to easily run electrical lines without cutting into the construction elements have limited the desirability of this approach.
Thus there is a need in the art for composite pre-formed building panels that overcome the above-described problems.